This invention relates to electric circuit breaker panelboards and more particularly to such panelboards which incorporate a pair of main circuit breakers for selectively switching the electrical supply to the panelboard between a primary source, such as the utility, and an alternate source, such as a generator. It is necessary that the main circuit breakers be prohibited from being contemporaneously operated to the ON condition. This invention relates particularly to a mechanical interlock for preventing contemporaneous operation of both main circuit breakers to the ON condition.
Mechanical interlocks which interconnect a pair of lever operated switches are well known. The assignee of this application has offered several variations of such interlocks. In circuit breaker panelboards, one such interlock has been mounted on the cover and has slidably interacted with the operator handles of tandemly (transversely) mounted circuit breakers. However, the interlock function is removed with the cover when servicing the panelboard in this version. Another panelboard has a sliding interlock mounted on a bracket which extends along the longitudinal center line of the panel. The ends of the bracket extend along the sides of the respective circuit breakers and are bolted directly to the panel or to the enclosure. One end of the bracket is offset from the center of the panel to clear a bus bar of the panelboard. A different length bracket is required for each panel accepting a different number of circuit breakers which translates into a different length for the panel. It is also necessary to modify the cover opening for the circuit breakers by notching the opening to receive the bracket at each end of the row of circuit breakers since the bracket extends beyond the side surface of the end circuit breakers. Thus, special covers are provided panelboards or loadcenters utilizing this version sliding interlock. The provision of special parts increases the cost of the item, both to manufacture and stock the different parts.